It is summertime and Green Knowe has been let to two women, the archaeologist Doctor Maud Biggin and her friend, Miss Sybilla Bun.

Doctor Biggin has invited her great-niece Ida and two "displaced" refugee children, Oskar and Ping, to stay with them at Green Knowe.

The children arrive and begin to explore the river and canals round Green Knowe by canoe.

The children's adventures here are based in their current time, though strongly fantasy-based; they meet a bus driver who's retreated from modern money-based society, see flying horses, meet a giant, and witness a Bronze Age moon ceremony.

The subtext, of homeless children being protected and healed by the house and its enchantments, is particularly strong.